1. Field of the Invention
The present invention relates to high dielectric constant ceramics which can be sintered at low temperatures and which are particularly adapted for use in electrical components.
2. Description of the Prior Art
Ceramic compositions find substantial applications in the electrical arts in the fabrication of electrical devices. One such application is in forming multilayer ceramic composites, which generally comprise a plurality of layers of a ceramic insulating material and a plurality of layers of a conductive metal material.
To date, substantially all ceramic materials available for use in forming such multilayer ceramic composites either illustrate a low dielectric constant or can be sintered only at high temperatures, e.g., 1250.degree. - 1650.degree.C. or higher.
Accordingly, multilayer ceramic composites as are in current use are basically limited to layers comprising insulators (the ceramic) and conductors (the metallurgy involved), and when it is desired to derive some function other than an insulating or conducting function from the multilayer ceramic composite, it is necessary to attach a micro-miniature discrete device thereto, after the fabrication of the multilayer ceramic composite, for example, a discrete decoupling capacitor.
Such multilayer ceramic composites are described in, for example, "Laminated Ceramics", Schwartz, et al., Proc. Electron. Comp. Conf. (Washington, D. C., 1967), page 17; "Ceramics for Packaging", Wilcox, Solid State Technology, 14, 1971, page 40; "A Fabrication Technique for Multi-layer Ceramic Modules", Kaiser, et al., Solid State Technology, May 1972, page 35; and "Metal-Ceramic Constraints for Multi-layer Electronic Packages", Chance, et al., Proceedings of the IEEE, 59, 1455 (1971).
Some experimenters have reported the development of low temperature high dielectric constant squeegee paste formulations for screening applications. These screen deposited high dielectric films (approximately 1 to 2 mils thick) remain porous after sintering. Specialized processing techniques coupled with vitreous encapsulants are used to achieve dielectric films with high capacitance values.